PSMB4 is a member of the peptidase T1B family. The 20S Proteasome chamber holds structural alpha subunits and predominantly catalytic beta subunits. The two external rings in the proteasome contain seven alpha subunits each and the two internal rings contain of seven beta subunits each. PSMB4 is a beta subunit of the 20S Proteasome that is spread all over the eukaryotic cells in large quantities and cleaves peptides in an ATP/ubiquitin-dependent process in a non-lysosomal pathway.
